A semiconductor memory may be classified into two types depending on whether it can hold the stored information when it loses power: a volatile memory and a non-volatile memory. With the popularity of portable electronic devices, the non-volatile memory has become more and more important in the memory market. Although the current FLASH technology is the mainstream of the non-volatile memory market, with the advancing of the semiconductor technical node, the FLASH technology is experiencing a series of bottlenecks such as a high operating voltage, a size that cannot be reduced, and a short holding time. It is reported that the limitation of the FLASH technology is around 16 nm. The scientific community and industry are looking for a next-generation non-volatile memory that can replace the FLASH technology. A Resistive Random Access Memory (RRAM) has become a research focus of the new non-volatile memory due to advantages of a low operating voltage, non-destructive read, a fast operation speed, a simple structure, easy integration, and the like. However, there is a serious crosstalk problem in the resistive random access memory array. Such crosstalk problem becomes more serious as the array expands, seriously affecting the reliability of the resistive random access memory and hindering its application.
At present, methods for solving the crosstalk problem of the resistive random access memory include: integrating a resistive random access memory with a MOS transistor (the 1T1R structure), connecting a resistive random access memory with an external diode (the 1D1R structure), and connecting a resistive random access memory with a selector in series (the 1S1R structure). In the 1T1R structure, since an area of a memory unit mainly depends on an area of the transistor, advantages of the simple structure and the small device area of RRAM cannot be given full play. The 1D1R is weak in limiting the leakage current as compared with the 1S1R. Therefore, the 1S1R structure is ideal to solve the crosstalk problem at present.
In the resistive random access memory having the 1S1R structure, a selector having a high current density, a high selection ratio and high durability is beneficial in improving the performance of the resistive random access memory having the 1S1R structure.